I would first try carbon or chem pure plus but I also like to put water polishing fiber or really a piece of cloth made by deep blue above my filter sock to skim the particles before it gets into the sock really clears up the tank. If you take that same cloth to a local fabric store they can match it up so you can get a whole roll for the same price as the small piece you will buy from deep blue. If you want to spend a little more money buy a carbon reactor and use the cloth, your water should look great. Frequent water changes always help as well.